Commons CLI

Links

http://jakarta.apache.org/commons/cli/
sample-commons-cli - sample code.

Alternatives

Maven

<dependency>
  <groupId>commons-cli</groupId>
  <artifactId>commons-cli</artifactId>
  <version>1.0</version>
</dependency>

Options

I created a getOptions() method. This sample code creates two types of Option:

The help and create options are simple boolean values, they are either specified on the command line (or not).

The file option has an associated value (a key/value pair).

private static final String OPTION_CREATE = "create";
private static final String OPTION_FILE = "file";
private static final String OPTION_HELP = "help";

private static Options getOptions() {
    Option create = new Option(OPTION_CREATE, "create a new repository.");
    Option help = new Option(OPTION_HELP, "print this message");
    Option file = OptionBuilder.withArgName(OPTION_FILE)
        .hasArg()
        .withDescription("add this document to the repository.")
        .create(OPTION_FILE);

    Options options = new Options();
    options.addOption(help);
    options.addOption(create);
    options.addOption(file);
    return options;
}

These options are used by the command line parser:

try {
    CommandLineParser parser = new GnuParser();
    CommandLine commandLine = parser.parse(getOptions(), args);
    ...
} catch (ParseException e) {
    System.err.println("Parsing failed.  Reason: " + e.getMessage());
}

The command line can be checked to see which options have been set (note the getOptionValue() method which returns the value of the file name):

if (commandLine.hasOption(OPTION_HELP)) {
   ...
}
if (commandLine.hasOption(OPTION_CREATE)) {
    ...
}
if (commandLine.hasOption(OPTION_FILE)) {
    String fileName = commandLine.getOptionValue(OPTION_FILE);
    ...
}

You can display help for the command line parameters (this code uses the getOptions() method which I created above):

new HelpFormatter().printHelp(MyClass.class.getName(), getOptions());